The present invention relates to cellular radio and telephone networks. These networks generally consist of mobile communications units (e.g., cellular telephones) which users employ to send radio signals carrying voice data over the air to other users. A mobile unit sends a signal which is received by a base station for the area or "cell" in which the mobile unit is located. The base station forwards the signal to a mobile services switching center, which routes the signal to its destination. This destination may be a ground-based telephone network or another base station which will re-broadcast the signal to another mobile unit. In either case, the signal is routed through a cellular telecommunications network before being either re-broadcast to another mobile unit or forwarded to the ground-based telephone network.
The cellular telecommunications network referenced above includes base stations strategically located in a geographical service area (each including an antenna, a base station controller, and a transceiver). Each base station is connected to a mobile switching center, with each mobile switching center serving several base stations. The mobile switching center is, generally, a small facility located between the base stations it serves and a centralized facility for the network. A home location register (HLR) is located at the centralized network facility, and serves all the mobile switching centers for the network. The HLR stores and provides access to network subscriber data. The HLR stores, for example, data describing a network subscriber's home network, type or level of service, and other subscription information. Each mobile switching center contains a visitors' location register ("VLR"), which registers users who access the network, but who are not listed in the network HLR because they are geographically located outside their home network when they access the cellular communications system. The VLR communicates with HLRs across the system to obtain user data about the users who access the network.
In addition to sending voice data signals carrying voice data, mobile units send digital messages to a telecommunications network. These messages can be used to, for example, change a subscriber's level of service, change a subscriber's service options, or change a subscriber's registered number to which incoming calls to the subscriber are to be forwarded. Like voice data signals, messages are also received by base stations and forwarded to mobile services switching centers. However, messages are then processed by the network, rather than forwarded to, or linked in communication with, another user. The messages may be processed and implemented by the HLR or another component of the network designed to act on the information specified in the message. The messages can operate as commands with regard to these components. These components of communications networks generally comprise standard micro-computers which are programmed to receive digital messages from mobile units forwarded via a base station. The computers, based on the messages, perform operations such as changing a subscriber's service options, or changing a number to which a subscriber's calls should be forwarded.
Current telecommunications systems have the capability of remote feature control, allowing a subscriber to, for example, establish an account, change a password, change a level of service, or change other service features such as call forwarding options. The current remote feature control systems receive messages through an HLR. All these functions are performed within the telecommunications network without the need for forwarding messages to outside, often incompatible, systems operated by outside vendors.
In current systems, messages are received by an HLR and either processed within the HLR or processed by another component of the network developed to perform the function specified by the message. The component processes the message according to the message contents and initiates the feature requested by the message. For example, a message requesting an updating of a call forwarding number contains a certain code signaling the network that it is a call forwarding number update request. A network component reads this code and determines that the message is not to be terminated within that component, but should be forwarded to a component within the network specifically designed to handle call forwarding. The component in which the message is to be terminated then initiates the call forwarding number updating sequence.
Current systems provide only for forwarding of messages within a network. New applications for the use of over-the-air digital messages require the forwarding of messages outside the network. Beyond changing user and service options, digital messages transmitted by mobile units can be used, for example, to provide information from remote locations to centralized databases (e.g. gas, water, or electric meter readings provided directly into a company database), or to transmit a specific geographical location of a user, or to provide commands to remotely-located devices (e.g. a power on/power off command).
U.S. Pat. No. 5,577,102 describes a system for processing short messages in a cellular telephone network. The system is designed to be a simple method for transmitting short messages from one subscriber on a cellular network to another subscriber. A message is received by a mobile switching center, which then checks the message address, stores the message, communicates with an HLR to obtain routing information, and transmits the message to the intended subscriber. This system receives, processes, and forwards digital messages within a cellular telecommunications network. It does not forward messages outside the network.
U.S. Pat. No. 5,428,665 describes a method for managing supplementary service procedures in a global system for mobile communications. Mobile stations send messages which are to be processed either in a mobile services switching center/visitor location register (MSC/VLR), or in a home location register (HLR). The MSC/VLR forwards messages destined for the HLR to the HLR, without seeing their contents or processing them in any other way. Messages to be terminated within the MSC/VLR are kept by the MSC/VLR and processed internally.
U.S. Pat. No. 5,594,740 describes a method and apparatus for using the control channels of an existing cellular telephone network to transmit and receive two-way wireless data messages. The system includes manipulation, translation, and encryption of control channel data bits, and provides for application-specific messaging on the control channels of an existing telecommunications network. This system does not provide for forwarding of application-specific messages outside a telecommunications network.